1. Field of the Invention
The invention relates to a connection device for a fluid line, comprising a connection unit having a sleeve-like insert body fitted by being plugged in a socket in a metallic holding body, anchoring means, constituted by one or more projections, being provided on the outer periphery of the insert body for anchoring in the socket.
2. Description of the Prior Art
Connection devices of this type, as described for example in the European patent publication 0 723 103 B1, are utilized to be able to connect fluid lines with fluid power equipment such as a valve or drive or the like. In the case of the connection device in accordance with the said European patent publication 0 723 103 B1 a connection unit is provided, whose component in the form of an insert body is inserted into the socket of a holding body and anchored in this socket. The holding body is in this case directly designed in the form of a component of the fluid power equipment, fitting by plugging taking place so that projection-like anchoring means provided on the outer periphery of the insert body bite into the wall of the socket and produce an interlocking connection so that the insert body is held immovably in the socket in the axial direction.
Connection devices of this type do possess the advantage that during fitting the connection unit it is possible to do without any screwing operation. On the other hand it has however turned out that firm holding of the insert body in the holding bodies of metalxe2x80x94for example of injection cast aluminumxe2x80x94can not be ensured under all states in a reliable manner, because the anchoring means constituted by one or more projections are subject to such deformation on biting into the hard material of the holding body or are even shorn off, that same are unable to perform the anchoring function or not perform it to the required degree.
Accordingly one object of the present invention is to provide a connection device of the type initially mentioned which ensures firm anchoring, even in the case of a holding body consisting of metal, in the socket after fitting therein by plugging.
In order to achieve such aim the connection device comprises a retaining ring of synthetic resin material, which is fixed in an annular groove, provided at the inner periphery of the socket, of the holding body, so that same may bear axially in either direction in relation to the holding body, the insert body being inserted coaxially into the retaining ring and having its anchoring means biting into the synthetic resin material of the holding ring.
This means that conditions are created in the socket of the metallic holding body as regards the anchoring measures which are comparable with those in the case of a holding body consisting of synthetic resin material, the insert body not having its anchoring means biting into the pertinent hard material of the metallic holding body but rather into the softer synthetic resin material of the retaining ring placed in the socket. The retaining ring itself is so axially locked on the holding body that it can bear in either axial direction on the holding body, something which ensures a firm retention of the insert body both in the case of regular fitting by plugging as part a press fitting and also in the case of later tension loading. The insert body is indirectly anchored, that is to say by the intermediary of the retaining ring of synthetic resin material, on the metallic holding body.
A further advantage produced with the design in accordance with the invention is that in the case of pulsating internal pressure loading normally occurring during operation, the resulting varying axial loading is taken up by the toothed engagement between the anchoring means and the retaining ring, the retaining ring being able, given a suitable design, to bear over a large area on the holding body. This means that shearing off and detachment at the point of anchoring engagement, as occurs in the prior art, is prevented when the anchoring means of the insert body directly cooperate with the metallic surface of the holding body.
Further advantageous developments of the invention are defined in the dependent claims.
The anchoring means provided on the insert body preferably consist of metal and may be designed in the form of a direct one-piece component of the insert body.
The anchoring means may for instance comprise a plurality of annular projections placed in sequence with an axial distance between them, which are more especially arranged respectively concentrically in relation to insert body and have a toothed shape. However, as has turned out, optimum anchoring engagement is ensured if the anchoring means biting into the holding body only consist of one annular radial projection.
The desired reliable anchoring of the retaining ring in the socket of the holding body may be ensured in a particularly simple manner if the retaining ring is set in an annular groove whose axially facing flanks are opposite to the axial end sides of the retaining ring so that the retaining ring may bear against same. It is in this manner that a particularly simple possibility is provided of holding the retaining ring only by frictional engagement at the flanks of the annular groove and without additional attachment measures such as bonding or press fitting or the like in the socket.
The fitting of the retaining ring in place is particularly simple if it is slotted at one point of its periphery so that it may be compressed elastically for insertion into the annular groove temporarily with a reduction of its external cross section. The retaining ring may for instance be inserted in the compressed state, it then expanding again on reaching the annular groove automatically and snapping into the annular groove. This fitting operation may be facilitated by providing a small degree of play between the retaining ring and the annular groove.
As a material for the retaining ring the use of an elastomeric material is recommended, particularly satisfactory results having been obtained with polyoxymethylene (POM).
An other particularly advantageous measure is such that the inner diameter of the outer section, to the fore of the retaining ring in the axial direction, of the socket is made larger than the inner diameter of the retaining ring in the fitted state, this being in conjunction with a further setting of the diameter such that the inner diameter of the above mentioned preceding outer section of the socket is the same as the outer diameter, defined by the anchoring means, of the insert body or preferably is somewhat larger than it. This means that during fitting by plugging of the insert body an excessively high load of the anchoring means owing to possible contact with the hard material of the holding body is prevented, it even being possible to prevent contact completely, something which reduces, or even completely excludes the danger of shearing off the anchoring means on press fitting the insert body.
For fixing the fluid line, which is to be connected, it is possible to provide holding means at the inner periphery of the insert body, for instance in the form of resiliently elastically movable claw elements, which after insertion of the fluid duct may act on the outer periphery thereof. A design which is advantageous in this case is such that the claw elements are designed as a component of an annular body attached to the insert body.
It is furthermore possible to provide a release body which is able to be moved more particularly axially, using which body it is possible to so act so manually on the holding means oppositely that same perform a release movement in the radially outward direction in order to release a previously inserted fluid duct.
Although it is in principle possible to design the connection device generally as a separate component group, which is then installed at the intended site of application, particular advantages are to be had more particularly if the holding body of the connection device is directly constituted by a component of a fluid power device, as for instance by the housing of such equipment.
In what follows an account will be given of the invention with reference to the accompanying drawings.